From 4a9179d151e045361e92847b548879090a3020eb Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:56:24 -0400 Subject: [PATCH 01/14] Documentation: remove a "future work" item from the MIDX docs One of the items listed as "future work" in the MIDX's technical documentation is to extend the format to allow MIDXs to be written incrementally across multiple layers. This was suggested all the way back in ceab693d1f (multi-pack-index: add design document, 2018-07-12), and implemented in b9497848df (Merge branch 'tb/incremental-midx-part-1', 2024-08-19). Let's remove it accordingly. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- Documentation/technical/multi-pack-index.adoc | 10 ---------- 1 file changed, 10 deletions(-) diff --git a/Documentation/technical/multi-pack-index.adoc b/Documentation/technical/multi-pack-index.adoc index cc063b30be..dea6486f88 100644 --- a/Documentation/technical/multi-pack-index.adoc +++ b/Documentation/technical/multi-pack-index.adoc @@ -167,16 +167,6 @@ m->num_objects_in_base`). Future Work ----------- -- The multi-pack-index allows many packfiles, especially in a context - where repacking is expensive (such as a very large repo), or - unexpected maintenance time is unacceptable (such as a high-demand - build machine). However, the multi-pack-index needs to be rewritten - in full every time. We can extend the format to be incremental, so - writes are fast. By storing a small "tip" multi-pack-index that - points to large "base" MIDX files, we can keep writes fast while - still reducing the number of binary searches required for object - lookups. - - If the multi-pack-index is extended to store a "stable object order" (a function Order(hash) = integer that is constant for a given hash, even as the multi-pack-index is updated) then MIDX bitmaps could be From 4887bdd4c7bd97e3eeccfc113fd97605b1a3d9ba Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:56:28 -0400 Subject: [PATCH 02/14] Documentation: describe incremental MIDX bitmaps Prepare to implement support for reachability bitmaps for the new incremental multi-pack index (MIDX) feature over the following commits. This commit begins by first describing the relevant format and usage details for incremental MIDX bitmaps. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- Documentation/technical/multi-pack-index.adoc | 72 +++++++++++++++++++ 1 file changed, 72 insertions(+) diff --git a/Documentation/technical/multi-pack-index.adoc b/Documentation/technical/multi-pack-index.adoc index dea6486f88..ffda70aa13 100644 --- a/Documentation/technical/multi-pack-index.adoc +++ b/Documentation/technical/multi-pack-index.adoc @@ -164,6 +164,78 @@ objects_nr($H2) + objects_nr($H1) + i (in the C implementation, this is often computed as `i + m->num_objects_in_base`). +=== Pseudo-pack order for incremental MIDXs + +The original implementation of multi-pack reachability bitmaps defined +the pseudo-pack order in linkgit:gitformat-pack[5] (see the section +titled "multi-pack-index reverse indexes") roughly as follows: + +____ +In short, a MIDX's pseudo-pack is the de-duplicated concatenation of +objects in packs stored by the MIDX, laid out in pack order, and the +packs arranged in MIDX order (with the preferred pack coming first). +____ + +In the incremental MIDX design, we extend this definition to include +objects from multiple layers of the MIDX chain. The pseudo-pack order +for incremental MIDXs is determined by concatenating the pseudo-pack +ordering for each layer of the MIDX chain in order. Formally two objects +`o1` and `o2` are compared as follows: + +1. If `o1` appears in an earlier layer of the MIDX chain than `o2`, then + `o1` sorts ahead of `o2`. + +2. Otherwise, if `o1` and `o2` appear in the same MIDX layer, and that + MIDX layer has no base, then if one of `pack(o1)` and `pack(o2)` is + preferred and the other is not, then the preferred one sorts ahead of + the non-preferred one. If there is a base layer (i.e. the MIDX layer + is not the first layer in the chain), then if `pack(o1)` appears + earlier in that MIDX layer's pack order, then `o1` sorts ahead of + `o2`. Likewise if `pack(o2)` appears earlier, then the opposite is + true. + +3. Otherwise, `o1` and `o2` appear in the same pack, and thus in the + same MIDX layer. Sort `o1` and `o2` by their offset within their + containing packfile. + +Note that the preferred pack is a property of the MIDX chain, not the +individual layers themselves. Fundamentally we could introduce a +per-layer preferred pack, but this is less relevant now that we can +perform multi-pack reuse across the set of packs in a MIDX. + +=== Reachability bitmaps and incremental MIDXs + +Each layer of an incremental MIDX chain may have its objects (and the +objects from any previous layer in the same MIDX chain) represented in +its own `*.bitmap` file. + +The structure of a `*.bitmap` file belonging to an incremental MIDX +chain is identical to that of a non-incremental MIDX bitmap, or a +classic single-pack bitmap. Since objects are added to the end of the +incremental MIDX's pseudo-pack order (see above), it is possible to +extend a bitmap when appending to the end of a MIDX chain. + +(Note: it is possible likewise to compress a contiguous sequence of MIDX +incremental layers, and their `*.bitmap` files into a single layer and +`*.bitmap`, but this is not yet implemented.) + +The object positions used are global within the pseudo-pack order, so +subsequent layers will have, for example, `m->num_objects_in_base` +number of `0` bits in each of their four type bitmaps. This follows from +the fact that we only write type bitmap entries for objects present in +the layer immediately corresponding to the bitmap). + +Note also that only the bitmap pertaining to the most recent layer in an +incremental MIDX chain is used to store reachability information about +the interesting and uninteresting objects in a reachability query. +Earlier bitmap layers are only used to look up commit and pseudo-merge +bitmaps from that layer, as well as the type-level bitmaps for objects +in that layer. + +To simplify the implementation, type-level bitmaps are iterated +simultaneously, and their results are OR'd together to avoid recursively +calling internal bitmap functions. + Future Work ----------- From 8331c17b7961736ac69b74d26af579048ad77866 Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:56:31 -0400 Subject: [PATCH 03/14] pack-revindex: prepare for incremental MIDX bitmaps Prepare the reverse index machinery to handle object lookups in an incremental MIDX bitmap. These changes are broken out across a few functions: - load_midx_revindex() learns to use the appropriate MIDX filename depending on whether the given 'struct multi_pack_index *' is incremental or not. - pack_pos_to_midx() and midx_to_pack_pos() now both take in a global object position in the MIDX pseudo-pack order, and find the earliest containing MIDX (similar to midx.c::midx_for_object(). - midx_pack_order_cmp() adjusts its call to pack_pos_to_midx() by the number of objects in the base (since 'vb - midx->revindx_data' is relative to the containing MIDX, and pack_pos_to_midx() expects a global position). Likewise, this function adjusts its output by adding m->num_objects_in_base to return a global position out through the `*pos` pointer. Together, these changes are sufficient to use the multi-pack index's reverse index format for incremental multi-pack reachability bitmaps. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- pack-bitmap.c | 43 +++++++++++++++++++++++++++++++------------ pack-revindex.c | 34 +++++++++++++++++++++++++--------- 2 files changed, 56 insertions(+), 21 deletions(-) diff --git a/pack-bitmap.c b/pack-bitmap.c index 6406953d32..87f3b5cf4d 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -170,6 +170,15 @@ static struct ewah_bitmap *read_bitmap_1(struct bitmap_index *index) return read_bitmap(index->map, index->map_size, &index->map_pos); } +static uint32_t bitmap_num_objects_total(struct bitmap_index *index) +{ + if (index->midx) { + struct multi_pack_index *m = index->midx; + return m->num_objects + m->num_objects_in_base; + } + return index->pack->num_objects; +} + static uint32_t bitmap_num_objects(struct bitmap_index *index) { if (index->midx) @@ -924,7 +933,7 @@ static inline int bitmap_position_extended(struct bitmap_index *bitmap_git, if (pos < kh_end(positions)) { int bitmap_pos = kh_value(positions, pos); - return bitmap_pos + bitmap_num_objects(bitmap_git); + return bitmap_pos + bitmap_num_objects_total(bitmap_git); } return -1; @@ -992,7 +1001,7 @@ static int ext_index_add_object(struct bitmap_index *bitmap_git, bitmap_pos = kh_value(eindex->positions, hash_pos); } - return bitmap_pos + bitmap_num_objects(bitmap_git); + return bitmap_pos + bitmap_num_objects_total(bitmap_git); } struct bitmap_show_data { @@ -1342,11 +1351,17 @@ struct ewah_bitmap *pseudo_merge_bitmap_for_commit(struct bitmap_index *bitmap_g if (pos < 0 || pos >= bitmap_num_objects(bitmap_git)) goto done; + /* + * Use bitmap-relative positions instead of offsetting + * by bitmap_git->num_objects_in_base because we use + * this to find a match in pseudo_merge_for_parents(), + * and pseudo-merge groups cannot span multiple bitmap + * layers. + */ bitmap_set(parents, pos); } - match = pseudo_merge_for_parents(&bitmap_git->pseudo_merges, - parents); + match = pseudo_merge_for_parents(&bitmap_git->pseudo_merges, parents); done: bitmap_free(parents); @@ -1500,7 +1515,9 @@ static void show_extended_objects(struct bitmap_index *bitmap_git, for (i = 0; i < eindex->count; ++i) { struct object *obj; - if (!bitmap_get(objects, st_add(bitmap_num_objects(bitmap_git), i))) + if (!bitmap_get(objects, + st_add(bitmap_num_objects_total(bitmap_git), + i))) continue; obj = eindex->objects[i]; @@ -1679,7 +1696,7 @@ static void filter_bitmap_exclude_type(struct bitmap_index *bitmap_git, * them individually. */ for (i = 0; i < eindex->count; i++) { - size_t pos = st_add(i, bitmap_num_objects(bitmap_git)); + size_t pos = st_add(i, bitmap_num_objects_total(bitmap_git)); if (eindex->objects[i]->type == type && bitmap_get(to_filter, pos) && !bitmap_get(tips, pos)) @@ -1705,7 +1722,7 @@ static unsigned long get_size_by_pos(struct bitmap_index *bitmap_git, oi.sizep = &size; - if (pos < bitmap_num_objects(bitmap_git)) { + if (pos < bitmap_num_objects_total(bitmap_git)) { struct packed_git *pack; off_t ofs; @@ -1728,8 +1745,9 @@ static unsigned long get_size_by_pos(struct bitmap_index *bitmap_git, die(_("unable to get size of %s"), oid_to_hex(&oid)); } } else { + size_t eindex_pos = pos - bitmap_num_objects_total(bitmap_git); struct eindex *eindex = &bitmap_git->ext_index; - struct object *obj = eindex->objects[pos - bitmap_num_objects(bitmap_git)]; + struct object *obj = eindex->objects[eindex_pos]; if (oid_object_info_extended(bitmap_repo(bitmap_git), &obj->oid, &oi, 0) < 0) die(_("unable to get size of %s"), oid_to_hex(&obj->oid)); @@ -1882,7 +1900,7 @@ static void filter_packed_objects_from_bitmap(struct bitmap_index *bitmap_git, uint32_t objects_nr; size_t i, pos; - objects_nr = bitmap_num_objects(bitmap_git); + objects_nr = bitmap_num_objects_total(bitmap_git); pos = objects_nr / BITS_IN_EWORD; if (pos > result->word_alloc) @@ -2419,7 +2437,7 @@ static uint32_t count_object_type(struct bitmap_index *bitmap_git, for (i = 0; i < eindex->count; ++i) { if (eindex->objects[i]->type == type && bitmap_get(objects, - st_add(bitmap_num_objects(bitmap_git), i))) + st_add(bitmap_num_objects_total(bitmap_git), i))) count++; } @@ -2820,7 +2838,7 @@ uint32_t *create_bitmap_mapping(struct bitmap_index *bitmap_git, BUG("rebuild_existing_bitmaps: missing required rev-cache " "extension"); - num_objects = bitmap_num_objects(bitmap_git); + num_objects = bitmap_num_objects_total(bitmap_git); CALLOC_ARRAY(reposition, num_objects); for (i = 0; i < num_objects; ++i) { @@ -2963,7 +2981,8 @@ static off_t get_disk_usage_for_extended(struct bitmap_index *bitmap_git) struct object *obj = eindex->objects[i]; if (!bitmap_get(result, - st_add(bitmap_num_objects(bitmap_git), i))) + st_add(bitmap_num_objects_total(bitmap_git), + i))) continue; if (oid_object_info_extended(bitmap_repo(bitmap_git), &obj->oid, diff --git a/pack-revindex.c b/pack-revindex.c index d3832478d9..d3faab6a37 100644 --- a/pack-revindex.c +++ b/pack-revindex.c @@ -383,8 +383,14 @@ int load_midx_revindex(struct multi_pack_index *m) trace2_data_string("load_midx_revindex", the_repository, "source", "rev"); - get_midx_filename_ext(m->repo->hash_algo, &revindex_name, m->object_dir, - get_midx_checksum(m), MIDX_EXT_REV); + if (m->has_chain) + get_split_midx_filename_ext(m->repo->hash_algo, &revindex_name, + m->object_dir, get_midx_checksum(m), + MIDX_EXT_REV); + else + get_midx_filename_ext(m->repo->hash_algo, &revindex_name, + m->object_dir, get_midx_checksum(m), + MIDX_EXT_REV); ret = load_revindex_from_disk(revindex_name.buf, m->num_objects, @@ -471,11 +477,15 @@ off_t pack_pos_to_offset(struct packed_git *p, uint32_t pos) uint32_t pack_pos_to_midx(struct multi_pack_index *m, uint32_t pos) { + while (m && pos < m->num_objects_in_base) + m = m->base_midx; + if (!m) + BUG("NULL multi-pack-index for object position: %"PRIu32, pos); if (!m->revindex_data) BUG("pack_pos_to_midx: reverse index not yet loaded"); - if (m->num_objects <= pos) + if (m->num_objects + m->num_objects_in_base <= pos) BUG("pack_pos_to_midx: out-of-bounds object at %"PRIu32, pos); - return get_be32(m->revindex_data + pos); + return get_be32(m->revindex_data + pos - m->num_objects_in_base); } struct midx_pack_key { @@ -491,7 +501,8 @@ static int midx_pack_order_cmp(const void *va, const void *vb) const struct midx_pack_key *key = va; struct multi_pack_index *midx = key->midx; - uint32_t versus = pack_pos_to_midx(midx, (uint32_t*)vb - (const uint32_t *)midx->revindex_data); + size_t pos = (uint32_t *)vb - (const uint32_t *)midx->revindex_data; + uint32_t versus = pack_pos_to_midx(midx, pos + midx->num_objects_in_base); uint32_t versus_pack = nth_midxed_pack_int_id(midx, versus); off_t versus_offset; @@ -529,9 +540,9 @@ static int midx_key_to_pack_pos(struct multi_pack_index *m, { uint32_t *found; - if (key->pack >= m->num_packs) + if (key->pack >= m->num_packs + m->num_packs_in_base) BUG("MIDX pack lookup out of bounds (%"PRIu32" >= %"PRIu32")", - key->pack, m->num_packs); + key->pack, m->num_packs + m->num_packs_in_base); /* * The preferred pack sorts first, so determine its identifier by * looking at the first object in pseudo-pack order. @@ -551,7 +562,8 @@ static int midx_key_to_pack_pos(struct multi_pack_index *m, if (!found) return -1; - *pos = found - m->revindex_data; + *pos = (found - m->revindex_data) + m->num_objects_in_base; + return 0; } @@ -559,9 +571,13 @@ int midx_to_pack_pos(struct multi_pack_index *m, uint32_t at, uint32_t *pos) { struct midx_pack_key key; + while (m && at < m->num_objects_in_base) + m = m->base_midx; + if (!m) + BUG("NULL multi-pack-index for object position: %"PRIu32, at); if (!m->revindex_data) BUG("midx_to_pack_pos: reverse index not yet loaded"); - if (m->num_objects <= at) + if (m->num_objects + m->num_objects_in_base <= at) BUG("midx_to_pack_pos: out-of-bounds object at %"PRIu32, at); key.pack = nth_midxed_pack_int_id(m, at); From f31a17cea5f6f66436e20f5dcefb6a0464238864 Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:56:34 -0400 Subject: [PATCH 04/14] pack-bitmap.c: open and store incremental bitmap layers Prepare the pack-bitmap machinery to work with incremental MIDXs by adding a new "base" field to keep track of the bitmap index associated with the previous MIDX layer. The changes in this commit are mostly boilerplate to open the correct bitmap(s), add them to the chain of bitmap layers along the "base" pointer, ensure that the correct packs and their reverse indexes are loaded across MIDX layers, etc. While we're at it, keep track of a base_nr field to indicate how many bitmap layers (including the current bitmap) exist. This will be used in a future commit to allocate an array of 'struct ewah_bitmap' pointers to collect all of the respective type bitmaps among all layers to initialize a multi-EWAH iterator. Subsequent commits will teach the functions within the pack-bitmap machinery how to interact with these new fields. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- pack-bitmap.c | 62 +++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 48 insertions(+), 14 deletions(-) diff --git a/pack-bitmap.c b/pack-bitmap.c index 87f3b5cf4d..e84211de15 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -54,6 +54,16 @@ struct bitmap_index { struct packed_git *pack; struct multi_pack_index *midx; + /* + * If using a multi-pack index chain, 'base' points to the + * bitmap index corresponding to this bitmap's midx->base_midx. + * + * base_nr indicates how many layers precede this one, and is + * zero when base is NULL. + */ + struct bitmap_index *base; + uint32_t base_nr; + /* mmapped buffer of the whole bitmap index */ unsigned char *map; size_t map_size; /* size of the mmaped buffer */ @@ -386,8 +396,15 @@ static int load_bitmap_entries_v1(struct bitmap_index *index) char *midx_bitmap_filename(struct multi_pack_index *midx) { struct strbuf buf = STRBUF_INIT; - get_midx_filename_ext(midx->repo->hash_algo, &buf, midx->object_dir, - get_midx_checksum(midx), MIDX_EXT_BITMAP); + if (midx->has_chain) + get_split_midx_filename_ext(midx->repo->hash_algo, &buf, + midx->object_dir, + get_midx_checksum(midx), + MIDX_EXT_BITMAP); + else + get_midx_filename_ext(midx->repo->hash_algo, &buf, + midx->object_dir, get_midx_checksum(midx), + MIDX_EXT_BITMAP); return strbuf_detach(&buf, NULL); } @@ -454,16 +471,21 @@ static int open_midx_bitmap_1(struct bitmap_index *bitmap_git, goto cleanup; } - for (i = 0; i < bitmap_git->midx->num_packs; i++) { - if (prepare_midx_pack(bitmap_repo(bitmap_git), - bitmap_git->midx, - i)) { + for (i = 0; i < bitmap_git->midx->num_packs + bitmap_git->midx->num_packs_in_base; i++) { + if (prepare_midx_pack(bitmap_repo(bitmap_git), bitmap_git->midx, i)) { warning(_("could not open pack %s"), bitmap_git->midx->pack_names[i]); goto cleanup; } } + if (midx->base_midx) { + bitmap_git->base = prepare_midx_bitmap_git(midx->base_midx); + bitmap_git->base_nr = bitmap_git->base->base_nr + 1; + } else { + bitmap_git->base_nr = 0; + } + return 0; cleanup: @@ -515,6 +537,7 @@ static int open_pack_bitmap_1(struct bitmap_index *bitmap_git, struct packed_git bitmap_git->map_size = xsize_t(st.st_size); bitmap_git->map = xmmap(NULL, bitmap_git->map_size, PROT_READ, MAP_PRIVATE, fd, 0); bitmap_git->map_pos = 0; + bitmap_git->base_nr = 0; close(fd); if (load_bitmap_header(bitmap_git) < 0) { @@ -534,8 +557,7 @@ static int open_pack_bitmap_1(struct bitmap_index *bitmap_git, struct packed_git static int load_reverse_index(struct repository *r, struct bitmap_index *bitmap_git) { if (bitmap_is_midx(bitmap_git)) { - uint32_t i; - int ret; + struct multi_pack_index *m; /* * The multi-pack-index's .rev file is already loaded via @@ -544,10 +566,15 @@ static int load_reverse_index(struct repository *r, struct bitmap_index *bitmap_ * But we still need to open the individual pack .rev files, * since we will need to make use of them in pack-objects. */ - for (i = 0; i < bitmap_git->midx->num_packs; i++) { - ret = load_pack_revindex(r, bitmap_git->midx->packs[i]); - if (ret) - return ret; + for (m = bitmap_git->midx; m; m = m->base_midx) { + uint32_t i; + int ret; + + for (i = 0; i < m->num_packs; i++) { + ret = load_pack_revindex(r, m->packs[i]); + if (ret) + return ret; + } } return 0; } @@ -573,6 +600,13 @@ static int load_bitmap(struct repository *r, struct bitmap_index *bitmap_git) if (!bitmap_git->table_lookup && load_bitmap_entries_v1(bitmap_git) < 0) goto failed; + if (bitmap_git->base) { + if (!bitmap_is_midx(bitmap_git)) + BUG("non-MIDX bitmap has non-NULL base bitmap index"); + if (load_bitmap(r, bitmap_git->base) < 0) + goto failed; + } + return 0; failed: @@ -657,10 +691,9 @@ struct bitmap_index *prepare_bitmap_git(struct repository *r) struct bitmap_index *prepare_midx_bitmap_git(struct multi_pack_index *midx) { - struct repository *r = midx->repo; struct bitmap_index *bitmap_git = xcalloc(1, sizeof(*bitmap_git)); - if (!open_midx_bitmap_1(bitmap_git, midx) && !load_bitmap(r, bitmap_git)) + if (!open_midx_bitmap_1(bitmap_git, midx)) return bitmap_git; free_bitmap_index(bitmap_git); @@ -2901,6 +2934,7 @@ void free_bitmap_index(struct bitmap_index *b) close_midx_revindex(b->midx); } free_pseudo_merge_map(&b->pseudo_merges); + free_bitmap_index(b->base); free(b); } From ae61324f0a6124534a245b70d55d63b5abf3e5d4 Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:56:37 -0400 Subject: [PATCH 05/14] pack-bitmap.c: teach `bitmap_for_commit()` about incremental MIDXs The pack-bitmap machinery uses `bitmap_for_commit()` to locate the EWAH-compressed bitmap corresponding to some given commit object. Teach this function about incremental MIDX bitmaps by teaching it to recur on earlier bitmap layers when it fails to find a given commit in the current layer. The changes to do so are as follows: - Avoid initializing hash_pos at its declaration, since bitmap_for_commit() is now a recursive function and may receive a NULL bitmap_index pointer as its first argument. - In cases where we would previously return NULL (to indicate that a lookup failed and the given bitmap_index does not contain an entry corresponding to the given commit), recursively call the function on the previous bitmap layer. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- pack-bitmap.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/pack-bitmap.c b/pack-bitmap.c index e84211de15..17f1087fba 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -941,18 +941,21 @@ corrupt: struct ewah_bitmap *bitmap_for_commit(struct bitmap_index *bitmap_git, struct commit *commit) { - khiter_t hash_pos = kh_get_oid_map(bitmap_git->bitmaps, - commit->object.oid); + khiter_t hash_pos; + if (!bitmap_git) + return NULL; + + hash_pos = kh_get_oid_map(bitmap_git->bitmaps, commit->object.oid); if (hash_pos >= kh_end(bitmap_git->bitmaps)) { struct stored_bitmap *bitmap = NULL; if (!bitmap_git->table_lookup) - return NULL; + return bitmap_for_commit(bitmap_git->base, commit); /* this is a fairly hot codepath - no trace2_region please */ /* NEEDSWORK: cache misses aren't recorded */ bitmap = lazy_bitmap_for_commit(bitmap_git, commit); if (!bitmap) - return NULL; + return bitmap_for_commit(bitmap_git->base, commit); return lookup_stored_bitmap(bitmap); } return lookup_stored_bitmap(kh_value(bitmap_git->bitmaps, hash_pos)); From f77dbf028510100ae7334c3d0e8fbd80a725e303 Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:56:40 -0400 Subject: [PATCH 06/14] pack-bitmap.c: teach `show_objects_for_type()` about incremental MIDXs Since we may ask for a pack_id that is in an earlier MIDX layer relative to the one corresponding to our bitmap, use nth_midxed_pack() instead of accessing the ->packs array directly. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- pack-bitmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/pack-bitmap.c b/pack-bitmap.c index 17f1087fba..f3ef9e43ef 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -1636,7 +1636,7 @@ static void show_objects_for_type( nth_midxed_object_oid(&oid, m, index_pos); pack_id = nth_midxed_pack_int_id(m, index_pos); - pack = bitmap_git->midx->packs[pack_id]; + pack = nth_midxed_pack(bitmap_git->midx, pack_id); } else { index_pos = pack_pos_to_index(bitmap_git->pack, pos + offset); ofs = pack_pos_to_offset(bitmap_git->pack, pos + offset); From 3886c7262170e2b7a2ed574ddefda2664695230a Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:56:43 -0400 Subject: [PATCH 07/14] pack-bitmap.c: support bitmap pack-reuse with incremental MIDXs In a similar fashion as previous commits in the first phase of incremental MIDXs, enumerate not just the packs in the current incremental MIDX layer, but previous ones as well. Likewise, in reuse_partial_packfile_from_bitmap(), when reusing only a single pack from a MIDX, use the oldest layer's preferred pack as it is likely to contain the largest number of reusable sections. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- pack-bitmap.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/pack-bitmap.c b/pack-bitmap.c index f3ef9e43ef..5ff1bbfd54 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -2335,7 +2335,8 @@ void reuse_partial_packfile_from_bitmap(struct bitmap_index *bitmap_git, multi_pack_reuse = 0; if (multi_pack_reuse) { - for (i = 0; i < bitmap_git->midx->num_packs; i++) { + struct multi_pack_index *m = bitmap_git->midx; + for (i = 0; i < m->num_packs + m->num_packs_in_base; i++) { struct bitmapped_pack pack; if (nth_bitmapped_pack(r, bitmap_git->midx, &pack, i) < 0) { warning(_("unable to load pack: '%s', disabling pack-reuse"), @@ -2361,14 +2362,18 @@ void reuse_partial_packfile_from_bitmap(struct bitmap_index *bitmap_git, uint32_t pack_int_id; if (bitmap_is_midx(bitmap_git)) { + struct multi_pack_index *m = bitmap_git->midx; uint32_t preferred_pack_pos; - if (midx_preferred_pack(bitmap_git->midx, &preferred_pack_pos) < 0) { + while (m->base_midx) + m = m->base_midx; + + if (midx_preferred_pack(m, &preferred_pack_pos) < 0) { warning(_("unable to compute preferred pack, disabling pack-reuse")); return; } - pack = bitmap_git->midx->packs[preferred_pack_pos]; + pack = nth_midxed_pack(m, preferred_pack_pos); pack_int_id = preferred_pack_pos; } else { pack = bitmap_git->pack; From faab03f9a16cbca85415b73504eb95e6b8ed3d6b Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:56:46 -0400 Subject: [PATCH 08/14] pack-bitmap.c: teach `rev-list --test-bitmap` about incremental MIDXs Implement support for the special `--test-bitmap` mode of `git rev-list` when using incremental MIDXs. The bitmap_test_data structure is extended to contain a "base" pointer that mirrors the structure of the bitmap chain that it is being used to test. When we find a commit to test, we first chase down the ->base pointer to find the appropriate bitmap_test_data for the bitmap layer that the given commit is contained within, and then perform the test on that bitmap. In order to implement this, light modifications are made to bitmap_for_commit() to reimplement it in terms of a new function, find_bitmap_for_commit(), which fills out a pointer which indicates the bitmap layer which contains the given commit. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- pack-bitmap.c | 107 ++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 86 insertions(+), 21 deletions(-) diff --git a/pack-bitmap.c b/pack-bitmap.c index 5ff1bbfd54..65ad631ce1 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -938,8 +938,9 @@ corrupt: return NULL; } -struct ewah_bitmap *bitmap_for_commit(struct bitmap_index *bitmap_git, - struct commit *commit) +static struct ewah_bitmap *find_bitmap_for_commit(struct bitmap_index *bitmap_git, + struct commit *commit, + struct bitmap_index **found) { khiter_t hash_pos; if (!bitmap_git) @@ -949,18 +950,30 @@ struct ewah_bitmap *bitmap_for_commit(struct bitmap_index *bitmap_git, if (hash_pos >= kh_end(bitmap_git->bitmaps)) { struct stored_bitmap *bitmap = NULL; if (!bitmap_git->table_lookup) - return bitmap_for_commit(bitmap_git->base, commit); + return find_bitmap_for_commit(bitmap_git->base, commit, + found); /* this is a fairly hot codepath - no trace2_region please */ /* NEEDSWORK: cache misses aren't recorded */ bitmap = lazy_bitmap_for_commit(bitmap_git, commit); if (!bitmap) - return bitmap_for_commit(bitmap_git->base, commit); + return find_bitmap_for_commit(bitmap_git->base, commit, + found); + if (found) + *found = bitmap_git; return lookup_stored_bitmap(bitmap); } + if (found) + *found = bitmap_git; return lookup_stored_bitmap(kh_value(bitmap_git->bitmaps, hash_pos)); } +struct ewah_bitmap *bitmap_for_commit(struct bitmap_index *bitmap_git, + struct commit *commit) +{ + return find_bitmap_for_commit(bitmap_git, commit, NULL); +} + static inline int bitmap_position_extended(struct bitmap_index *bitmap_git, const struct object_id *oid) { @@ -2513,6 +2526,8 @@ struct bitmap_test_data { struct bitmap *tags; struct progress *prg; size_t seen; + + struct bitmap_test_data *base_tdata; }; static void test_bitmap_type(struct bitmap_test_data *tdata, @@ -2521,6 +2536,11 @@ static void test_bitmap_type(struct bitmap_test_data *tdata, enum object_type bitmap_type = OBJ_NONE; int bitmaps_nr = 0; + if (bitmap_is_midx(tdata->bitmap_git)) { + while (pos < tdata->bitmap_git->midx->num_objects_in_base) + tdata = tdata->base_tdata; + } + if (bitmap_get(tdata->commits, pos)) { bitmap_type = OBJ_COMMIT; bitmaps_nr++; @@ -2584,13 +2604,57 @@ static void test_show_commit(struct commit *commit, void *data) display_progress(tdata->prg, ++tdata->seen); } +static uint32_t bitmap_total_entry_count(struct bitmap_index *bitmap_git) +{ + uint32_t total = 0; + do { + total = st_add(total, bitmap_git->entry_count); + bitmap_git = bitmap_git->base; + } while (bitmap_git); + + return total; +} + +static void bitmap_test_data_prepare(struct bitmap_test_data *tdata, + struct bitmap_index *bitmap_git) +{ + memset(tdata, 0, sizeof(struct bitmap_test_data)); + + tdata->bitmap_git = bitmap_git; + tdata->base = bitmap_new(); + tdata->commits = ewah_to_bitmap(bitmap_git->commits); + tdata->trees = ewah_to_bitmap(bitmap_git->trees); + tdata->blobs = ewah_to_bitmap(bitmap_git->blobs); + tdata->tags = ewah_to_bitmap(bitmap_git->tags); + + if (bitmap_git->base) { + tdata->base_tdata = xmalloc(sizeof(struct bitmap_test_data)); + bitmap_test_data_prepare(tdata->base_tdata, bitmap_git->base); + } +} + +static void bitmap_test_data_release(struct bitmap_test_data *tdata) +{ + if (!tdata) + return; + + bitmap_test_data_release(tdata->base_tdata); + free(tdata->base_tdata); + + bitmap_free(tdata->base); + bitmap_free(tdata->commits); + bitmap_free(tdata->trees); + bitmap_free(tdata->blobs); + bitmap_free(tdata->tags); +} + void test_bitmap_walk(struct rev_info *revs) { struct object *root; struct bitmap *result = NULL; size_t result_popcnt; struct bitmap_test_data tdata; - struct bitmap_index *bitmap_git; + struct bitmap_index *bitmap_git, *found; struct ewah_bitmap *bm; if (!(bitmap_git = prepare_bitmap_git(revs->repo))) @@ -2599,17 +2663,28 @@ void test_bitmap_walk(struct rev_info *revs) if (revs->pending.nr != 1) die(_("you must specify exactly one commit to test")); - fprintf_ln(stderr, "Bitmap v%d test (%d entries%s)", + fprintf_ln(stderr, "Bitmap v%d test (%d entries%s, %d total)", bitmap_git->version, bitmap_git->entry_count, - bitmap_git->table_lookup ? "" : " loaded"); + bitmap_git->table_lookup ? "" : " loaded", + bitmap_total_entry_count(bitmap_git)); root = revs->pending.objects[0].item; - bm = bitmap_for_commit(bitmap_git, (struct commit *)root); + bm = find_bitmap_for_commit(bitmap_git, (struct commit *)root, &found); if (bm) { fprintf_ln(stderr, "Found bitmap for '%s'. %d bits / %08x checksum", - oid_to_hex(&root->oid), (int)bm->bit_size, ewah_checksum(bm)); + oid_to_hex(&root->oid), + (int)bm->bit_size, ewah_checksum(bm)); + + if (bitmap_is_midx(found)) + fprintf_ln(stderr, "Located via MIDX '%s'.", + hash_to_hex_algop(get_midx_checksum(found->midx), + revs->repo->hash_algo)); + else + fprintf_ln(stderr, "Located via pack '%s'.", + hash_to_hex_algop(found->pack->hash, + revs->repo->hash_algo)); result = ewah_to_bitmap(bm); } @@ -2626,16 +2701,10 @@ void test_bitmap_walk(struct rev_info *revs) if (prepare_revision_walk(revs)) die(_("revision walk setup failed")); - tdata.bitmap_git = bitmap_git; - tdata.base = bitmap_new(); - tdata.commits = ewah_to_bitmap(bitmap_git->commits); - tdata.trees = ewah_to_bitmap(bitmap_git->trees); - tdata.blobs = ewah_to_bitmap(bitmap_git->blobs); - tdata.tags = ewah_to_bitmap(bitmap_git->tags); + bitmap_test_data_prepare(&tdata, bitmap_git); tdata.prg = start_progress(revs->repo, "Verifying bitmap entries", result_popcnt); - tdata.seen = 0; traverse_commit_list(revs, &test_show_commit, &test_show_object, &tdata); @@ -2647,11 +2716,7 @@ void test_bitmap_walk(struct rev_info *revs) die(_("mismatch in bitmap results")); bitmap_free(result); - bitmap_free(tdata.base); - bitmap_free(tdata.commits); - bitmap_free(tdata.trees); - bitmap_free(tdata.blobs); - bitmap_free(tdata.tags); + bitmap_test_data_release(&tdata); free_bitmap_index(bitmap_git); } From db17e777c884b9aa2ba532a96a5439e9be09174b Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:56:49 -0400 Subject: [PATCH 09/14] pack-bitmap.c: compute disk-usage with incremental MIDXs In a similar fashion as previous commits, use nth_midxed_pack() instead of accessing the MIDX's ->packs array directly to support incremental MIDXs. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- pack-bitmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/pack-bitmap.c b/pack-bitmap.c index 65ad631ce1..4086277de8 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -1779,7 +1779,7 @@ static unsigned long get_size_by_pos(struct bitmap_index *bitmap_git, uint32_t midx_pos = pack_pos_to_midx(bitmap_git->midx, pos); uint32_t pack_id = nth_midxed_pack_int_id(bitmap_git->midx, midx_pos); - pack = bitmap_git->midx->packs[pack_id]; + pack = nth_midxed_pack(bitmap_git->midx, pack_id); ofs = nth_midxed_offset(bitmap_git->midx, midx_pos); } else { pack = bitmap_git->pack; @@ -3049,7 +3049,7 @@ static off_t get_disk_usage_for_type(struct bitmap_index *bitmap_git, off_t offset = nth_midxed_offset(bitmap_git->midx, midx_pos); uint32_t pack_id = nth_midxed_pack_int_id(bitmap_git->midx, midx_pos); - struct packed_git *pack = bitmap_git->midx->packs[pack_id]; + struct packed_git *pack = nth_midxed_pack(bitmap_git->midx, pack_id); if (offset_to_pack_pos(pack, offset, &pack_pos) < 0) { struct object_id oid; From e2837e29e62805502ad17ea3b1eae941f8963625 Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:56:56 -0400 Subject: [PATCH 10/14] pack-bitmap.c: apply pseudo-merge commits with incremental MIDXs Prepare for using pseudo-merges with incremental MIDX bitmaps by attempting to apply pseudo-merges from each layer when encountering a given commit during a walk. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- pack-bitmap.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/pack-bitmap.c b/pack-bitmap.c index 4086277de8..1d1e1a65ca 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -1082,10 +1082,15 @@ static unsigned apply_pseudo_merges_for_commit_1(struct bitmap_index *bitmap_git struct commit *commit, uint32_t commit_pos) { - int ret; + struct bitmap_index *curr = bitmap_git; + int ret = 0; - ret = apply_pseudo_merges_for_commit(&bitmap_git->pseudo_merges, - result, commit, commit_pos); + while (curr) { + ret += apply_pseudo_merges_for_commit(&curr->pseudo_merges, + result, commit, + commit_pos); + curr = curr->base; + } if (ret) pseudo_merges_satisfied_nr += ret; From 5551ccfe97a573c058ee1ccb516770886fd17489 Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:56:59 -0400 Subject: [PATCH 11/14] ewah: implement `struct ewah_or_iterator` While individual bitmap layers store different commit, type-level, and pseudo-merge bitmaps, only the top-most layer is used to compute reachability traversals. Many functions which implement the aforementioned traversal rely on enumerating the results according to the type-level bitmaps, and so would benefit from a conceptual type-level bitmap that spans multiple layers. Implement `struct ewah_or_iterator` which is capable of enumerating multiple EWAH bitmaps at once, and OR-ing the results together. When initialized with, for example, all of the commit type bitmaps from each layer, callers can pretend as if they are enumerating a large type-level bitmap which contains the commits from *all* bitmap layers. There are a couple of alternative approaches which were considered: - Decompress each EWAH bitmap and OR them together, enumerating a single (non-EWAH) bitmap. This would work, but has the disadvantage of decompressing a potentially large bitmap, which may not be necessary if the caller does not wish to read all of it. - Recursively call bitmap internal functions, reusing the "result" and "haves" bitmap from the top-most layer. This approach resembles the original implementation of this feature, but is inefficient in that it both (a) requires significant refactoring to implement, and (b) enumerates large sections of later bitmaps which are all zeros (as they pertain to objects in earlier layers). (b) is not so bad in and of itself, but can cause significant slow-downs when combined with expensive loop bodies. This approach (enumerating an OR'd together version of all of the type-level bitmaps from each layer) produces a significantly more straightforward implementation with significantly less refactoring required in order to make it work. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- ewah/ewah_bitmap.c | 33 +++++++++++++++++++++++++++++++++ ewah/ewok.h | 12 ++++++++++++ 2 files changed, 45 insertions(+) diff --git a/ewah/ewah_bitmap.c b/ewah/ewah_bitmap.c index 67f8f588e0..056c410efb 100644 --- a/ewah/ewah_bitmap.c +++ b/ewah/ewah_bitmap.c @@ -371,6 +371,39 @@ void ewah_iterator_init(struct ewah_iterator *it, struct ewah_bitmap *parent) read_new_rlw(it); } +void ewah_or_iterator_init(struct ewah_or_iterator *it, + struct ewah_bitmap **parents, size_t nr) +{ + size_t i; + + memset(it, 0, sizeof(*it)); + + ALLOC_ARRAY(it->its, nr); + for (i = 0; i < nr; i++) + ewah_iterator_init(&it->its[it->nr++], parents[i]); +} + +int ewah_or_iterator_next(eword_t *next, struct ewah_or_iterator *it) +{ + eword_t buf, out = 0; + size_t i; + int ret = 0; + + for (i = 0; i < it->nr; i++) + if (ewah_iterator_next(&buf, &it->its[i])) { + out |= buf; + ret = 1; + } + + *next = out; + return ret; +} + +void ewah_or_iterator_release(struct ewah_or_iterator *it) +{ + free(it->its); +} + void ewah_xor( struct ewah_bitmap *ewah_i, struct ewah_bitmap *ewah_j, diff --git a/ewah/ewok.h b/ewah/ewok.h index 5e357e2493..c29d354236 100644 --- a/ewah/ewok.h +++ b/ewah/ewok.h @@ -148,6 +148,18 @@ void ewah_iterator_init(struct ewah_iterator *it, struct ewah_bitmap *parent); */ int ewah_iterator_next(eword_t *next, struct ewah_iterator *it); +struct ewah_or_iterator { + struct ewah_iterator *its; + size_t nr; +}; + +void ewah_or_iterator_init(struct ewah_or_iterator *it, + struct ewah_bitmap **parents, size_t nr); + +int ewah_or_iterator_next(eword_t *next, struct ewah_or_iterator *it); + +void ewah_or_iterator_release(struct ewah_or_iterator *it); + void ewah_xor( struct ewah_bitmap *ewah_i, struct ewah_bitmap *ewah_j, From e07af41139fe6d5f088dda2501ed754ef40b6399 Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:57:02 -0400 Subject: [PATCH 12/14] pack-bitmap.c: keep track of each layer's type bitmaps Prepare for reading the type-level bitmaps from previous bitmap layers by maintaining an array for each type, where each element in that type's array corresponds to one layer's bitmap for that type. These fields will be used in a later commit to instantiate the 'struct ewah_or_iterator' for each type. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- pack-bitmap.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 53 insertions(+), 4 deletions(-) diff --git a/pack-bitmap.c b/pack-bitmap.c index 1d1e1a65ca..5721fa7a0f 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -81,6 +81,23 @@ struct bitmap_index { struct ewah_bitmap *blobs; struct ewah_bitmap *tags; + /* + * Type index arrays when this bitmap is associated with an + * incremental multi-pack index chain. + * + * If n is the number of unique layers in the MIDX chain, then + * commits_all[n-1] is this structs 'commits' field, + * commits_all[n-2] is the commits field of this bitmap's + * 'base', and so on. + * + * When associated either with a non-incremental MIDX or a + * single packfile, these arrays each contain a single element. + */ + struct ewah_bitmap **commits_all; + struct ewah_bitmap **trees_all; + struct ewah_bitmap **blobs_all; + struct ewah_bitmap **tags_all; + /* Map from object ID -> `stored_bitmap` for all the bitmapped commits */ kh_oid_map_t *bitmaps; @@ -581,7 +598,32 @@ static int load_reverse_index(struct repository *r, struct bitmap_index *bitmap_ return load_pack_revindex(r, bitmap_git->pack); } -static int load_bitmap(struct repository *r, struct bitmap_index *bitmap_git) +static void load_all_type_bitmaps(struct bitmap_index *bitmap_git) +{ + struct bitmap_index *curr = bitmap_git; + size_t i = bitmap_git->base_nr; + + ALLOC_ARRAY(bitmap_git->commits_all, bitmap_git->base_nr + 1); + ALLOC_ARRAY(bitmap_git->trees_all, bitmap_git->base_nr + 1); + ALLOC_ARRAY(bitmap_git->blobs_all, bitmap_git->base_nr + 1); + ALLOC_ARRAY(bitmap_git->tags_all, bitmap_git->base_nr + 1); + + while (curr) { + bitmap_git->commits_all[i] = curr->commits; + bitmap_git->trees_all[i] = curr->trees; + bitmap_git->blobs_all[i] = curr->blobs; + bitmap_git->tags_all[i] = curr->tags; + + curr = curr->base; + if (curr && !i) + BUG("unexpected number of bitmap layers, expected %"PRIu32, + bitmap_git->base_nr + 1); + i -= 1; + } +} + +static int load_bitmap(struct repository *r, struct bitmap_index *bitmap_git, + int recursing) { assert(bitmap_git->map); @@ -603,10 +645,13 @@ static int load_bitmap(struct repository *r, struct bitmap_index *bitmap_git) if (bitmap_git->base) { if (!bitmap_is_midx(bitmap_git)) BUG("non-MIDX bitmap has non-NULL base bitmap index"); - if (load_bitmap(r, bitmap_git->base) < 0) + if (load_bitmap(r, bitmap_git->base, 1) < 0) goto failed; } + if (!recursing) + load_all_type_bitmaps(bitmap_git); + return 0; failed: @@ -682,7 +727,7 @@ struct bitmap_index *prepare_bitmap_git(struct repository *r) { struct bitmap_index *bitmap_git = xcalloc(1, sizeof(*bitmap_git)); - if (!open_bitmap(r, bitmap_git) && !load_bitmap(r, bitmap_git)) + if (!open_bitmap(r, bitmap_git) && !load_bitmap(r, bitmap_git, 0)) return bitmap_git; free_bitmap_index(bitmap_git); @@ -2052,7 +2097,7 @@ struct bitmap_index *prepare_bitmap_walk(struct rev_info *revs, * from disk. this is the point of no return; after this the rev_list * becomes invalidated and we must perform the revwalk through bitmaps */ - if (load_bitmap(revs->repo, bitmap_git) < 0) + if (load_bitmap(revs->repo, bitmap_git, 0) < 0) goto cleanup; if (!use_boundary_traversal) @@ -2985,6 +3030,10 @@ void free_bitmap_index(struct bitmap_index *b) ewah_pool_free(b->trees); ewah_pool_free(b->blobs); ewah_pool_free(b->tags); + free(b->commits_all); + free(b->trees_all); + free(b->blobs_all); + free(b->tags_all); if (b->bitmaps) { struct stored_bitmap *sb; kh_foreach_value(b->bitmaps, sb, { From 5999b44fcbe1e1638960314c65723c60be6aeb9c Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:57:05 -0400 Subject: [PATCH 13/14] pack-bitmap.c: use `ewah_or_iterator` for type bitmap iterators Now that we have initialized arrays for each bitmap layer's type bitmaps in the previous commit, adjust existing callers to use them in preparation for multi-layered bitmaps. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- pack-bitmap.c | 42 +++++++++++++++++++++++++++--------------- 1 file changed, 27 insertions(+), 15 deletions(-) diff --git a/pack-bitmap.c b/pack-bitmap.c index 5721fa7a0f..6f7fd94c36 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -1629,25 +1629,29 @@ static void show_extended_objects(struct bitmap_index *bitmap_git, } } -static void init_type_iterator(struct ewah_iterator *it, +static void init_type_iterator(struct ewah_or_iterator *it, struct bitmap_index *bitmap_git, enum object_type type) { switch (type) { case OBJ_COMMIT: - ewah_iterator_init(it, bitmap_git->commits); + ewah_or_iterator_init(it, bitmap_git->commits_all, + bitmap_git->base_nr + 1); break; case OBJ_TREE: - ewah_iterator_init(it, bitmap_git->trees); + ewah_or_iterator_init(it, bitmap_git->trees_all, + bitmap_git->base_nr + 1); break; case OBJ_BLOB: - ewah_iterator_init(it, bitmap_git->blobs); + ewah_or_iterator_init(it, bitmap_git->blobs_all, + bitmap_git->base_nr + 1); break; case OBJ_TAG: - ewah_iterator_init(it, bitmap_git->tags); + ewah_or_iterator_init(it, bitmap_git->tags_all, + bitmap_git->base_nr + 1); break; default: @@ -1664,7 +1668,7 @@ static void show_objects_for_type( size_t i = 0; uint32_t offset; - struct ewah_iterator it; + struct ewah_or_iterator it; eword_t filter; struct bitmap *objects = bitmap_git->result; @@ -1672,7 +1676,7 @@ static void show_objects_for_type( init_type_iterator(&it, bitmap_git, object_type); for (i = 0; i < objects->word_alloc && - ewah_iterator_next(&filter, &it); i++) { + ewah_or_iterator_next(&filter, &it); i++) { eword_t word = objects->words[i] & filter; size_t pos = (i * BITS_IN_EWORD); @@ -1714,6 +1718,8 @@ static void show_objects_for_type( show_reach(&oid, object_type, 0, hash, pack, ofs); } } + + ewah_or_iterator_release(&it); } static int in_bitmapped_pack(struct bitmap_index *bitmap_git, @@ -1765,7 +1771,7 @@ static void filter_bitmap_exclude_type(struct bitmap_index *bitmap_git, { struct eindex *eindex = &bitmap_git->ext_index; struct bitmap *tips; - struct ewah_iterator it; + struct ewah_or_iterator it; eword_t mask; uint32_t i; @@ -1782,7 +1788,7 @@ static void filter_bitmap_exclude_type(struct bitmap_index *bitmap_git, * packfile. */ for (i = 0, init_type_iterator(&it, bitmap_git, type); - i < to_filter->word_alloc && ewah_iterator_next(&mask, &it); + i < to_filter->word_alloc && ewah_or_iterator_next(&mask, &it); i++) { if (i < tips->word_alloc) mask &= ~tips->words[i]; @@ -1802,6 +1808,7 @@ static void filter_bitmap_exclude_type(struct bitmap_index *bitmap_git, bitmap_unset(to_filter, pos); } + ewah_or_iterator_release(&it); bitmap_free(tips); } @@ -1862,14 +1869,14 @@ static void filter_bitmap_blob_limit(struct bitmap_index *bitmap_git, { struct eindex *eindex = &bitmap_git->ext_index; struct bitmap *tips; - struct ewah_iterator it; + struct ewah_or_iterator it; eword_t mask; uint32_t i; tips = find_tip_objects(bitmap_git, tip_objects, OBJ_BLOB); for (i = 0, init_type_iterator(&it, bitmap_git, OBJ_BLOB); - i < to_filter->word_alloc && ewah_iterator_next(&mask, &it); + i < to_filter->word_alloc && ewah_or_iterator_next(&mask, &it); i++) { eword_t word = to_filter->words[i] & mask; unsigned offset; @@ -1897,6 +1904,7 @@ static void filter_bitmap_blob_limit(struct bitmap_index *bitmap_git, bitmap_unset(to_filter, pos); } + ewah_or_iterator_release(&it); bitmap_free(tips); } @@ -2528,12 +2536,12 @@ static uint32_t count_object_type(struct bitmap_index *bitmap_git, struct eindex *eindex = &bitmap_git->ext_index; uint32_t i = 0, count = 0; - struct ewah_iterator it; + struct ewah_or_iterator it; eword_t filter; init_type_iterator(&it, bitmap_git, type); - while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) { + while (i < objects->word_alloc && ewah_or_iterator_next(&filter, &it)) { eword_t word = objects->words[i++] & filter; count += ewah_bit_popcount64(word); } @@ -2545,6 +2553,8 @@ static uint32_t count_object_type(struct bitmap_index *bitmap_git, count++; } + ewah_or_iterator_release(&it); + return count; } @@ -3077,13 +3087,13 @@ static off_t get_disk_usage_for_type(struct bitmap_index *bitmap_git, { struct bitmap *result = bitmap_git->result; off_t total = 0; - struct ewah_iterator it; + struct ewah_or_iterator it; eword_t filter; size_t i; init_type_iterator(&it, bitmap_git, object_type); for (i = 0; i < result->word_alloc && - ewah_iterator_next(&filter, &it); i++) { + ewah_or_iterator_next(&filter, &it); i++) { eword_t word = result->words[i] & filter; size_t base = (i * BITS_IN_EWORD); unsigned offset; @@ -3124,6 +3134,8 @@ static off_t get_disk_usage_for_type(struct bitmap_index *bitmap_git, } } + ewah_or_iterator_release(&it); + return total; } From 27afc272c49137460fe9e58e1fcbe4c1d377b304 Mon Sep 17 00:00:00 2001 From: Taylor Blau Date: Thu, 20 Mar 2025 13:57:08 -0400 Subject: [PATCH 14/14] midx: implement writing incremental MIDX bitmaps Now that the pack-bitmap machinery has learned how to read and interact with an incremental MIDX bitmap, teach the pack-bitmap-write.c machinery (and relevant callers from within the MIDX machinery) to write such bitmaps. The details for doing so are mostly straightforward. The main changes are as follows: - find_object_pos() now makes use of an extra MIDX parameter which is used to locate the bit positions of objects which are from previous layers (and thus do not exist in the current layer's pack_order field). (Note also that the pack_order field is moved into struct write_midx_context to further simplify the callers for write_midx_bitmap()). - bitmap_writer_build_type_index() first determines how many objects precede the current bitmap layer and offsets the bits it sets in each respective type-level bitmap by that amount so they can be OR'd together. Signed-off-by: Taylor Blau Acked-by: Elijah Newren Signed-off-by: Junio C Hamano --- builtin/pack-objects.c | 3 +- midx-write.c | 57 ++++++++++------ pack-bitmap-write.c | 65 +++++++++++++----- pack-bitmap.h | 4 +- t/t5334-incremental-multi-pack-index.sh | 87 +++++++++++++++++++++++++ 5 files changed, 179 insertions(+), 37 deletions(-) diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c index 58a9b16126..a7e4bb7904 100644 --- a/builtin/pack-objects.c +++ b/builtin/pack-objects.c @@ -1397,7 +1397,8 @@ static void write_pack_file(void) if (write_bitmap_index) { bitmap_writer_init(&bitmap_writer, - the_repository, &to_pack); + the_repository, &to_pack, + NULL); bitmap_writer_set_checksum(&bitmap_writer, hash); bitmap_writer_build_type_index(&bitmap_writer, written_list); diff --git a/midx-write.c b/midx-write.c index 48d6558253..0897cbd829 100644 --- a/midx-write.c +++ b/midx-write.c @@ -647,16 +647,22 @@ static uint32_t *midx_pack_order(struct write_midx_context *ctx) return pack_order; } -static void write_midx_reverse_index(char *midx_name, unsigned char *midx_hash, - struct write_midx_context *ctx) +static void write_midx_reverse_index(struct write_midx_context *ctx, + const char *object_dir, + unsigned char *midx_hash) { struct strbuf buf = STRBUF_INIT; char *tmp_file; trace2_region_enter("midx", "write_midx_reverse_index", ctx->repo); - strbuf_addf(&buf, "%s-%s.rev", midx_name, hash_to_hex_algop(midx_hash, - ctx->repo->hash_algo)); + if (ctx->incremental) + get_split_midx_filename_ext(ctx->repo->hash_algo, &buf, + object_dir, midx_hash, + MIDX_EXT_REV); + else + get_midx_filename_ext(ctx->repo->hash_algo, &buf, object_dir, + midx_hash, MIDX_EXT_REV); tmp_file = write_rev_file_order(ctx->repo->hash_algo, NULL, ctx->pack_order, ctx->entries_nr, midx_hash, WRITE_REV); @@ -829,22 +835,29 @@ static struct commit **find_commits_for_midx_bitmap(uint32_t *indexed_commits_nr return cb.commits; } -static int write_midx_bitmap(struct repository *r, const char *midx_name, +static int write_midx_bitmap(struct write_midx_context *ctx, + const char *object_dir, const unsigned char *midx_hash, struct packing_data *pdata, struct commit **commits, uint32_t commits_nr, - uint32_t *pack_order, unsigned flags) { int ret, i; uint16_t options = 0; struct bitmap_writer writer; struct pack_idx_entry **index; - char *bitmap_name = xstrfmt("%s-%s.bitmap", midx_name, - hash_to_hex_algop(midx_hash, r->hash_algo)); + struct strbuf bitmap_name = STRBUF_INIT; - trace2_region_enter("midx", "write_midx_bitmap", r); + trace2_region_enter("midx", "write_midx_bitmap", ctx->repo); + + if (ctx->incremental) + get_split_midx_filename_ext(ctx->repo->hash_algo, &bitmap_name, + object_dir, midx_hash, + MIDX_EXT_BITMAP); + else + get_midx_filename_ext(ctx->repo->hash_algo, &bitmap_name, + object_dir, midx_hash, MIDX_EXT_BITMAP); if (flags & MIDX_WRITE_BITMAP_HASH_CACHE) options |= BITMAP_OPT_HASH_CACHE; @@ -861,7 +874,8 @@ static int write_midx_bitmap(struct repository *r, const char *midx_name, for (i = 0; i < pdata->nr_objects; i++) index[i] = &pdata->objects[i].idx; - bitmap_writer_init(&writer, r, pdata); + bitmap_writer_init(&writer, ctx->repo, pdata, + ctx->incremental ? ctx->base_midx : NULL); bitmap_writer_show_progress(&writer, flags & MIDX_PROGRESS); bitmap_writer_build_type_index(&writer, index); @@ -879,7 +893,7 @@ static int write_midx_bitmap(struct repository *r, const char *midx_name, * bitmap_writer_finish(). */ for (i = 0; i < pdata->nr_objects; i++) - index[pack_order[i]] = &pdata->objects[i].idx; + index[ctx->pack_order[i]] = &pdata->objects[i].idx; bitmap_writer_select_commits(&writer, commits, commits_nr); ret = bitmap_writer_build(&writer); @@ -887,14 +901,14 @@ static int write_midx_bitmap(struct repository *r, const char *midx_name, goto cleanup; bitmap_writer_set_checksum(&writer, midx_hash); - bitmap_writer_finish(&writer, index, bitmap_name, options); + bitmap_writer_finish(&writer, index, bitmap_name.buf, options); cleanup: free(index); - free(bitmap_name); + strbuf_release(&bitmap_name); bitmap_writer_free(&writer); - trace2_region_leave("midx", "write_midx_bitmap", r); + trace2_region_leave("midx", "write_midx_bitmap", ctx->repo); return ret; } @@ -1077,8 +1091,6 @@ static int write_midx_internal(struct repository *r, const char *object_dir, ctx.repo = r; ctx.incremental = !!(flags & MIDX_WRITE_INCREMENTAL); - if (ctx.incremental && (flags & MIDX_WRITE_BITMAP)) - die(_("cannot write incremental MIDX with bitmap")); if (ctx.incremental) strbuf_addf(&midx_name, @@ -1119,6 +1131,13 @@ static int write_midx_internal(struct repository *r, const char *object_dir, if (ctx.incremental) { struct multi_pack_index *m = ctx.base_midx; while (m) { + if (flags & MIDX_WRITE_BITMAP && load_midx_revindex(m)) { + error(_("could not load reverse index for MIDX %s"), + hash_to_hex_algop(get_midx_checksum(m), + m->repo->hash_algo)); + result = 1; + goto cleanup; + } ctx.num_multi_pack_indexes_before++; m = m->base_midx; } @@ -1387,7 +1406,7 @@ static int write_midx_internal(struct repository *r, const char *object_dir, if (flags & MIDX_WRITE_REV_INDEX && git_env_bool("GIT_TEST_MIDX_WRITE_REV", 0)) - write_midx_reverse_index(midx_name.buf, midx_hash, &ctx); + write_midx_reverse_index(&ctx, object_dir, midx_hash); if (flags & MIDX_WRITE_BITMAP) { struct packing_data pdata; @@ -1410,8 +1429,8 @@ static int write_midx_internal(struct repository *r, const char *object_dir, FREE_AND_NULL(ctx.entries); ctx.entries_nr = 0; - if (write_midx_bitmap(r, midx_name.buf, midx_hash, &pdata, - commits, commits_nr, ctx.pack_order, + if (write_midx_bitmap(&ctx, object_dir, + midx_hash, &pdata, commits, commits_nr, flags) < 0) { error(_("could not write multi-pack bitmap")); result = 1; diff --git a/pack-bitmap-write.c b/pack-bitmap-write.c index 34e86d4994..8a30853d2e 100644 --- a/pack-bitmap-write.c +++ b/pack-bitmap-write.c @@ -26,6 +26,8 @@ #include "alloc.h" #include "refs.h" #include "strmap.h" +#include "midx.h" +#include "pack-revindex.h" struct bitmapped_commit { struct commit *commit; @@ -43,7 +45,8 @@ static inline int bitmap_writer_nr_selected_commits(struct bitmap_writer *writer } void bitmap_writer_init(struct bitmap_writer *writer, struct repository *r, - struct packing_data *pdata) + struct packing_data *pdata, + struct multi_pack_index *midx) { memset(writer, 0, sizeof(struct bitmap_writer)); if (writer->bitmaps) @@ -51,6 +54,7 @@ void bitmap_writer_init(struct bitmap_writer *writer, struct repository *r, writer->bitmaps = kh_init_oid_map(); writer->pseudo_merge_commits = kh_init_oid_map(); writer->to_pack = pdata; + writer->midx = midx; string_list_init_dup(&writer->pseudo_merge_groups); @@ -113,6 +117,11 @@ void bitmap_writer_build_type_index(struct bitmap_writer *writer, struct pack_idx_entry **index) { uint32_t i; + uint32_t base_objects = 0; + + if (writer->midx) + base_objects = writer->midx->num_objects + + writer->midx->num_objects_in_base; writer->commits = ewah_new(); writer->trees = ewah_new(); @@ -142,19 +151,19 @@ void bitmap_writer_build_type_index(struct bitmap_writer *writer, switch (real_type) { case OBJ_COMMIT: - ewah_set(writer->commits, i); + ewah_set(writer->commits, i + base_objects); break; case OBJ_TREE: - ewah_set(writer->trees, i); + ewah_set(writer->trees, i + base_objects); break; case OBJ_BLOB: - ewah_set(writer->blobs, i); + ewah_set(writer->blobs, i + base_objects); break; case OBJ_TAG: - ewah_set(writer->tags, i); + ewah_set(writer->tags, i + base_objects); break; default: @@ -207,19 +216,37 @@ void bitmap_writer_push_commit(struct bitmap_writer *writer, static uint32_t find_object_pos(struct bitmap_writer *writer, const struct object_id *oid, int *found) { - struct object_entry *entry = packlist_find(writer->to_pack, oid); + struct object_entry *entry; + + entry = packlist_find(writer->to_pack, oid); + if (entry) { + uint32_t base_objects = 0; + if (writer->midx) + base_objects = writer->midx->num_objects + + writer->midx->num_objects_in_base; - if (!entry) { if (found) - *found = 0; - warning("Failed to write bitmap index. Packfile doesn't have full closure " - "(object %s is missing)", oid_to_hex(oid)); - return 0; + *found = 1; + return oe_in_pack_pos(writer->to_pack, entry) + base_objects; + } else if (writer->midx) { + uint32_t at, pos; + + if (!bsearch_midx(oid, writer->midx, &at)) + goto missing; + if (midx_to_pack_pos(writer->midx, at, &pos) < 0) + goto missing; + + if (found) + *found = 1; + return pos; } +missing: if (found) - *found = 1; - return oe_in_pack_pos(writer->to_pack, entry); + *found = 0; + warning("Failed to write bitmap index. Packfile doesn't have full closure " + "(object %s is missing)", oid_to_hex(oid)); + return 0; } static void compute_xor_offsets(struct bitmap_writer *writer) @@ -586,7 +613,7 @@ int bitmap_writer_build(struct bitmap_writer *writer) struct prio_queue queue = { compare_commits_by_gen_then_commit_date }; struct prio_queue tree_queue = { NULL }; struct bitmap_index *old_bitmap; - uint32_t *mapping; + uint32_t *mapping = NULL; int closed = 1; /* until proven otherwise */ if (writer->show_progress) @@ -1021,7 +1048,7 @@ void bitmap_writer_finish(struct bitmap_writer *writer, struct strbuf tmp_file = STRBUF_INIT; struct hashfile *f; off_t *offsets = NULL; - uint32_t i; + uint32_t i, base_objects; struct bitmap_disk_header header; @@ -1047,6 +1074,12 @@ void bitmap_writer_finish(struct bitmap_writer *writer, if (options & BITMAP_OPT_LOOKUP_TABLE) CALLOC_ARRAY(offsets, writer->to_pack->nr_objects); + if (writer->midx) + base_objects = writer->midx->num_objects + + writer->midx->num_objects_in_base; + else + base_objects = 0; + for (i = 0; i < bitmap_writer_nr_selected_commits(writer); i++) { struct bitmapped_commit *stored = &writer->selected[i]; int commit_pos = oid_pos(&stored->commit->object.oid, index, @@ -1055,7 +1088,7 @@ void bitmap_writer_finish(struct bitmap_writer *writer, if (commit_pos < 0) BUG(_("trying to write commit not in index")); - stored->commit_pos = commit_pos; + stored->commit_pos = commit_pos + base_objects; } write_selected_commits_v1(writer, f, offsets); diff --git a/pack-bitmap.h b/pack-bitmap.h index d7f4b8b8e9..dd0951088f 100644 --- a/pack-bitmap.h +++ b/pack-bitmap.h @@ -111,6 +111,7 @@ struct bitmap_writer { kh_oid_map_t *bitmaps; struct packing_data *to_pack; + struct multi_pack_index *midx; /* if appending to a MIDX chain */ struct bitmapped_commit *selected; unsigned int selected_nr, selected_alloc; @@ -125,7 +126,8 @@ struct bitmap_writer { }; void bitmap_writer_init(struct bitmap_writer *writer, struct repository *r, - struct packing_data *pdata); + struct packing_data *pdata, + struct multi_pack_index *midx); void bitmap_writer_show_progress(struct bitmap_writer *writer, int show); void bitmap_writer_set_checksum(struct bitmap_writer *writer, const unsigned char *sha1); diff --git a/t/t5334-incremental-multi-pack-index.sh b/t/t5334-incremental-multi-pack-index.sh index 26257e5660..d30d7253d6 100755 --- a/t/t5334-incremental-multi-pack-index.sh +++ b/t/t5334-incremental-multi-pack-index.sh @@ -44,4 +44,91 @@ test_expect_success 'convert incremental to non-incremental' ' compare_results_with_midx 'non-incremental MIDX conversion' +write_midx_layer () { + n=1 + if test -f $midx_chain + then + n="$(($(wc -l <$midx_chain) + 1))" + fi + + for i in 1 2 + do + test_commit $n.$i && + git repack -d || return 1 + done && + git multi-pack-index write --bitmap --incremental +} + +test_expect_success 'write initial MIDX layer' ' + git repack -ad && + write_midx_layer +' + +test_expect_success 'read bitmap from first MIDX layer' ' + git rev-list --test-bitmap 1.2 +' + +test_expect_success 'write another MIDX layer' ' + write_midx_layer +' + +test_expect_success 'midx verify with multiple layers' ' + test_path_is_file "$midx_chain" && + test_line_count = 2 "$midx_chain" && + + git multi-pack-index verify +' + +test_expect_success 'read bitmap from second MIDX layer' ' + git rev-list --test-bitmap 2.2 +' + +test_expect_success 'read earlier bitmap from second MIDX layer' ' + git rev-list --test-bitmap 1.2 +' + +test_expect_success 'show object from first pack' ' + git cat-file -p 1.1 +' + +test_expect_success 'show object from second pack' ' + git cat-file -p 2.2 +' + +for reuse in false single multi +do + test_expect_success "full clone (pack.allowPackReuse=$reuse)" ' + rm -fr clone.git && + + git config pack.allowPackReuse $reuse && + git clone --no-local --bare . clone.git + ' +done + +test_expect_success 'relink existing MIDX layer' ' + rm -fr "$midxdir" && + + GIT_TEST_MIDX_WRITE_REV=1 git multi-pack-index write --bitmap && + + midx_hash="$(test-tool read-midx --checksum $objdir)" && + + test_path_is_file "$packdir/multi-pack-index" && + test_path_is_file "$packdir/multi-pack-index-$midx_hash.bitmap" && + test_path_is_file "$packdir/multi-pack-index-$midx_hash.rev" && + + test_commit another && + git repack -d && + git multi-pack-index write --bitmap --incremental && + + test_path_is_missing "$packdir/multi-pack-index" && + test_path_is_missing "$packdir/multi-pack-index-$midx_hash.bitmap" && + test_path_is_missing "$packdir/multi-pack-index-$midx_hash.rev" && + + test_path_is_file "$midxdir/multi-pack-index-$midx_hash.midx" && + test_path_is_file "$midxdir/multi-pack-index-$midx_hash.bitmap" && + test_path_is_file "$midxdir/multi-pack-index-$midx_hash.rev" && + test_line_count = 2 "$midx_chain" + +' + test_done